Mr. and Mrs. North (with Frances Lockridge)
The Norths Meet Murder (1940)
Murder Out of Turn (1941)
A Pinch of Poison (1941)
Death on the Aisle (1942)
Hanged for a Sheep (1942)
Death Takes a Bow (1943)
Killing the Goose (1944)
Payoff for the Banker (1945)
Death of a Tall Man (1946)
Murder Within Murder (1946)
Untidy Murder (1947)
Murder Is Served (1948)
The Dishonest Murderer (1949)
Murder in a Hurry (1950)
Murder Comes First (1951)
Dead As a Dinosaur (1952)
Curtain for a Jester (1953)
Key to Death (1954)
Death of an Angel (1955)
     aka Mr & Mrs North and the Poisoned Playboy
Voyage into Violence (1956)
Long Skeleton (1958)
Murder Is Suggested (1959)
The Judge Is Reversed (1960)
Murder Has Its Points (1962)
Murder by the Book (1963)

Captain Heimrich
6. Death by Association (1952) (with Frances Lockridge)
     aka Trial by Terror
8. Death and the Gentle Bull (1954) (with Frances Lockridge)
     aka Killer in the Straw
10. Let Dead Enough Alone (1956) (with Frances Lockridge)
12. Accent on Murder (1958) (with Frances Lockridge)
13. Show Red for Danger (1960) (with Frances Lockridge)
14. With One Stone (1961) (with Frances Lockridge)
     aka No Dignity in Death
Think of Death (1947) (with Frances Lockridge)
I Want to Go Home (1948) (with Frances Lockridge)
Spin Your Web, Lady (1949) (with Frances Lockridge)
Foggy, Foggy Death (1950) (with Frances Lockridge)
A Client Is Cancelled (1951) (with Frances Lockridge)
Stand Up and Die (1953) (with Frances Lockridge)
Burnt Offering (1955) (with Frances Lockridge)
Practise to Deceive (1957) (with Frances Lockridge)
The Distant Clue (1963) (with Frances Lockridge)
First Come, First Kill (1963) (with Frances Lockridge)
Murder Can't Wait (1964)
Murder Roundabout (1966)
With Option to Die (1967)
A Risky Way to Kill (1969)
Inspector's Holiday (1971)
Not I Said the Sparrow (1973)
Dead Run (1976)
The Tenth Life (1977)

Death in the Mind (1945) (with G H Estabrooks)
A Matter of Taste (1949)
The Faceless Adversary (1956) (with Frances Lockridge)
     aka Case of the Murdered Redhead
The Tangled Cord (1957) (with Frances Lockridge)
Catch As Catch Can (1958) (with Frances Lockridge)
The Innocent House (1959) (with Frances Lockridge)
The Golden Man (1960) (with Frances Lockridge)
The Drill Is Death (1961) (with Frances Lockridge)
And Left for Dead (1961) (with Frances Lockridge)
Night of Shadows (1962) (with Frances Lockridge)
The Ticking Clock (1962) (with Frances Lockridge)
The Devious Ones (1964) (with Frances Lockridge)
     aka Four Hours to Fear
Quest for the Bogeyman (1964) (with Frances Lockridge)
Quest of the Bogeyman (1965) (with Frances Lockridge)
One Lady, Two Cats (1967)
Murder in False Face (1969)
Death in a Sunny Place (1971)
Troubled Journey (1971)

Troubled Journey / The Yellow Gold of Tiryns / Double Identity (1969) (with George Harmon Coxe and Helena Osborne)